Description Most deaths in developed countries occur in persons over the age of 70 years who suffer from multiple health conditions. The contribution of these multiple conditions to death may not be accurately or completely captured with current methods. The predominant algorithmic, adjudication method approach may be misleading, both over- and under-estimating the contribution of co-existing diseases and conditions. It is time to complement existing methods for assigning cause of death by determining the cumulative chronic and acute conditions contributing to death. The two Subaims of this project are to: 1) test the hypothesis that multiple co-occurring chronic and acute conditions contributed to the deaths in two cohorts of older adults;and 2) determine the extent (amount) of the contribution of these conditions to the deaths. The participants are members of 2 longitudinal cohorts of older adults. The Cardiovascular Health Study (CHS) has 5,888 participants, age 65+ years from 4 U.S. counties. The Medicare Current Beneficiary Study (MCBS) includes representative participants age 65+ years sampled across the nation. Both CHS and MCBS collected a wealth of health information including chronic and acute conditions and vital status. Proportional hazards models, incorporating time-dependent variables (important for studying the onset, occurrence and/or reoccurrence of conditions), will be used to derive the ratio of the hazard of death for individuals with and without specific conditions, while controlling for the other conditions (Subaim 1). The second Subaim expands on methods for determining the extent to which each condition contributes to death. The product of the analyses will be the amount of contribution to death of each condition in the final model. Individual conditions likely will make an independent contribution but will also contribute to death dependent on the presence of other conditions. Using innovative analytical techniques we will estimate the total contribution attributed to the conditions. An empirically-derived method reflecting the multiple conditions contributing to death should encourage better informed clinical decision-making and better alignment of research and reimbursement dollars with actual disease burden. With baby boomers heading into their late years, accurate estimates of the conditions contributing to mortality are essential for health and economic planning.